Although much work has been done in olefin polymerization catalysis, there is still a desire to improve the process. In particular, there is a need to provide a practical, commercially viable method of making polyolefins that can utilize the newer “single-site” catalyst components known in the art. There is great interest because, while lab scale processes may afford desirable polymers using, for example, metallocene catalyst components, commercial scale up is often hindered by problems such as reactor fouling. In particular, olefin polymerization reactions catalyzed using single-site catalyst components are often subject to uncontrollable phases, wherein the polymer agglomerates into large (greater than 1 cm) chunks or larger, and can often “sheet” on the inside surface of the reactor, causing, among other problems, a lack of heat removal in the reactor, and further “running away” of the polymerization. In these cases, the reactor must be shut down, resulting in costly delays and lack of commercial viability.
A promising class of single-site catalysts for commercial use includes those wherein the metal center has at least one extractable fluorine (or fluorine “leaving group”). Disclosures of such catalysts include US 20020032287; WO 97/07141; DE 43 32 009 A1; EP-A2 0 200 351; EP-A1 0 705 849; E. F. Murphy, et al., Synthesis and spectroscopic characterization of a series of substituted cyclopentadienyl Group 4 fluorides; crystal structure of the acetylacetonato complex [(acac)2(η5-C5Me5)Zr(μ-F)SnMe3Cl], DALTON, 1983 (1996); A. Herzog, et al., Reactions of (η5-C5Me5)ZrF3, (η5-C5Me4Et)ZrF3, (η5-C5M45)2ZrF2, (η5-C5Me5)HfF3, and (η5-C5Me5)TaF4 with AlMe3, Structure of the First Hafnium-Aluminum-Carbon Cluster, 15 ORGANOMETALLICS 909-917 (1996); F. Garbassi, et al., JOURNAL OF MOLECULAR CATALYSIS A: CHEMICAL 101 199-209 (1995); and W. Kaminsky, et al., Fluorinated Half-Sandwich Complexes as Catalysts in Syndiospecific Styrene Polymerization, 30(25) MACROMOLECULES 7647-7650 (1997). Use of such single site catalyst components in a olefin polymerization system is desirable, especially in gas-phase polyethylene polymerization.
With the growing use of such catalysts, there is a need to provide a practical method of making such catalysts. Typically, the production of the fluorine-containing catalyst component, or “fluorided” catalyst component, entails the reaction of a fluoriding agent with the corresponding “chlorided” catalyst component. The use of some common fluoriding agents presents many challenges, excessive cost among them. Other methods of fluoriding metallocene catalyst components are disclosed by Z. Xie et al., Synthesis, Molecular Structure, and Reactivity of Organolanthamide Fluoride Complexes, [{(Me3Si)2C5H3}2Ln(μ-F)]2 (Ln=La, Nd, Sm, Gd) and [(C5H5)2Ln(μ-F)(THF)]2 (Ln=Y, Yb), 17 ORGANOMETALLICS 3937-3944 (1998); E. F. Murphy et al. in Organometallic Fluorides: Compounds Containing Carbon-Metal-Fluorine Fragments of d-Block Metals, 97 CHEM. REV. 3425-3468 (1997); W. W. Lukens, Jr. et al. in A π-Donor Spectrochemical Series for X in (Me5C5)2TiX, and β-Agostic Interactions in X=Et and N(Me)Ph, 118 J. AM. CHEM. SOc. 1729-1728 (1996); and P. M. Druce et al. in Metallocene Halides: Part I Synthesis, Spectra, and Redistribution Equilibria of Di-π-cyclopentadienyl-Ti(IV), —Zr(M), and —Hf(IV), 14 J. CHEM. SOC. 2106-2110 (1969). However, these methods fall short of a desirable, cost effective commercial method of making fluorided metallocene catalyst components. What is needed is an improved method of producing fluorided catalyst components that will be more practical and beneficial to commercial olefin polymerization and oligomerization processes. The present invention is directed towards this improvement.